1. Technical Field
The present invention relates to an ink for inkjet, an ink cartridge using the ink, an inkjet recorder and an ink recorded matter.
2. Description of the Related Art
Inkjet recording methods are advantageous in comparison with other recording methods in that, since the process is simple, full colorization is easy and high-definition images can be obtained with even a simple apparatus configuration. Dye-based ink in which various hydrosoluble dyes are dissolved in water or a mixture of water and a hydrosoluble wetter is used as the ink for inkjet.
In recent years, demand for high-speed printing has continued to increase. However, problems such as curl occur after printing in a case in which aqueous ink is used for plain paper. Aqueous ink contains large amounts of water, which swells the fiber of the paper and results in curl.
On the other hand, with oil-based ink, since it does not contain water, curl is not a serious problem. However, the oil-based ink penetrates into a recording medium more deeply than aqueous ink, which degrades the image quality such that image density is low and blurring and strike-through significantly occur. In short, ink for inkjet recording satisfies the competing requirements of minimal curl and superior image quality has not been attained so far.
Methods of adding a particular sugar group, sugar alcohol, amide compound as an anti-curl agent to prevent curl of plain paper when aqueous ink is used are suggested. Although successful in some degree, these methods still face the problems of curl when printing images requiring a large amount of ink at a high speed.
JP-2005-297549-A describes methods of increasing the amount of solvent in aqueous ink to prevent occurrence of curl. However, since the ratio of the solvent increases, as in the case of the oil-based ink, the image quality is low and the viscosity of the ink tends to increase, which causes a problem with regard to ink discharge reliability.
A method of increasing the amount of hydrophobic solvent to prevent occurrence of curl is suggested. However, the results are unsatisfactory.
Currently, prevention of curl and improved image quality are incompatible.
JP-2012-107210-A proposes an ink including 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-methoxy-N,N-dimethylpropion amide. This ink produces the curl preventing effect, but an ink including a large amount of these materials has a problem of serious back curl after time passes.
Because of these reasons, a need exists for an ink for recording, capable of preventing curl and producing high-quality images when printing on plain papers.